Excessive buildup of cerebrospinal fluid (CSF) within the brain's ventricular system (hydrocephalus) is a disease that often seriously damages tissues in the central nervous system and may result in death if left untreated. The estimated prevalence in children is 1 in 500, with the excess intracranial pressure significantly impairing mental development, and often causing cranial bulging if occurring in infancy. Ventriculoperitoneal (VP) shunts have been the standard treatment since the early 1960s and have increased the survival rate and quality of life of pediatric hydrocephalus patients significantly. Despite these gains, malfunction and revision surgery are common occurrences. The rate of malfunction of VP shunts in children is estimated to be 40% in the first year after placement, and 10% per year after that. Current methods for diagnosing shunt malfunctions are often invasive, require ionizing radiation, or are expensive for the patient. The overall goal of te project is to develop a safe, cost-effective method for diagnosing shunt malfunctions using ultrasound. We propose a method for CSF flow assessment in a shunt catheter based on contrast-enhanced real-time ultrasound imaging and simultaneous motion estimation using a 2D cross correlation technique. Compared to current clinical imaging protocols, our approach is minimally invasive, cost-effective, and the examination can be performed in a doctor's office, ultimately saving the patient time and money. The objective of the current proposal is to develop and establish the feasibility of this new diagnostic imaging technique and to validate the methodology with phantom, tissue and animal studies. The immediate expected outcome of this project will be a device and associated software ready for preclinical and preliminary clinical testing.